September weather forecastStromness, United Kingdom
September
Weather in September
The first month of the autumn, September, is also a moderate month in Stromness, United Kingdom, with an average temperature fluctuating between 11.7°C (53.1°F) and 13.2°C (55.8°F).Temperature
The shift into September finds Stromness at an average high-temperature of a still moderate 13.2°C (55.8°F), closely comparable to August's conditions. Stromness, during the September nights, maintains an average temperature of 11.7°C (53.1°F), closely aligned with its daytime readings.Humidity
In Stromness, the average relative humidity in September is 83%.Rainfall
In Stromness, in September, it is raining for 18.9 days, with typically 45mm (1.77") of accumulated precipitation. Throughout the year, in Stromness, there are 233.4 rainfall days, and 572mm (22.52") of precipitation is accumulated.Snowfall
May through October are months without snowfall in Stromness.Sea temperature
In Stromness, the average seawater temperature in September is 12.9°C (55.2°F).Note: Being in 12.9°C (55.2°F) waters at 13°C (55.4°F) is discomforting, but anything below 10°C (50°F) can jeopardize breathing and induce cold shock, factoring in physical endurance.
Daylight
The average length of the day in September is 12h and 49min.On the first day of the month, sunrise is at 6:12 am and sunset at 8:13 pm. On the last day of September, sunrise is at 7:17 am and sunset at 6:48 pm BST.
Sunshine
The average sunshine in September is 6.1h.UV index
The months with the highest UV index are June, July and September, with an average maximum UV index of 4. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for the average person.Note: In September, the maximum UV index of 4 suggests these recommendations:
Take care. Persons with lighter skin might suffer burns in less than 30 minutes. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Stromness, United Kingdom
- Average high temperature in September: 13.2°C
The warmest month (with the highest average high temperature) is August (14.2°C).
The month with the lowest average high temperature is February (7°C).
- Average low temperature in September: 11.7°C
The month with the highest average low temperature is August (12.4°C).
The coldest month (with the lowest average low temperature) is February (5.5°C).
Average pressure in September
Stromness, United Kingdom
- Average pressure in September: 1010.7mbar
The months with the highest atmospheric pressure are May and June (1014.4mbar).
The month with the lowest atmospheric pressure is December (1003.7mbar).
Average wind speed in September
Stromness, United Kingdom
- Average wind speed in September: 29.6km/h
The windiest month (with the highest average wind speed) is January (38.7km/h).
The calmest months (with the lowest average wind speed) are June and July (22.5km/h).
Average humidity in September
Stromness, United Kingdom
- Average humidity in September: 83%
The month with the highest relative humidity is July (86%).
The months with the lowest relative humidity are January and December (75%).
Average rainfall in September
Stromness, United Kingdom
- Average rainfall in September: 45mm
The wettest months (with the highest rainfall) are January and December (60mm).
The driest month (with the least rainfall) is April (30mm).
Average rainfall days in September
Stromness, United Kingdom
- Average rainfall days in September: 18.9 days
The month with the highest number of rainy days is December (23.5 days).
The month with the least rainy days is June (15.5 days).
Average snowfall in September
Stromness, United Kingdom
- Average snowfall in September: 0mm
The month with the highest snowfall is February (5mm).
The months with the least snowfall are May, June, July, August, September and October (0mm).
Average snowfall days in September
Stromness, United Kingdom
- Average snowfall days in September: 0 days
The months with the highest number of snowfall days are February and March (1.2 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average sea temperature in September
Stromness, United Kingdom
- Average sea temperature in September: 12.9°C
The best month for swimming (with the highest average sea temperature) is August (13.3°C).
The coldest month (with the lowest average sea temperature) is March (7.3°C).
Average daylight in September /
Average sunshine in September
Stromness, United Kingdom
- Average daylight in September: 12h and 48min
The month with the longest days is June (Average daylight: 18h and 24min).
The month with the shortest days is December (Average daylight: 6h and 18min).
- Average sunshine in September: 6h and 6min
The month with the most sunshine is June (Average sunshine: 8h and 6min).
The month with the least sunshine is December (Average sunshine: 3h and 6min).
Average sunshine days in September
Stromness, United Kingdom
- Average sunshine days in September: 8.5 days
The month with the most sunshine days is May (11.4 days).
The month with the least sunshine days is December (4.8 days).
Average UV index in September
Stromness, United Kingdom
- Average UV index in September: 4
The months with the highest UV index are June, July and September (UV index 4).
The months with the lowest UV index are January, February, March and December (UV index 2).
Average cloud cover in September
Stromness, United Kingdom
- Average cloud cover in September: 60
The months with the most cloud cover are January and March (Cloud cover 67).
The months with the least cloud cover are April and May (Cloud cover 56).
Average visibility in September
Stromness, United Kingdom
- Average visibility in September: 10km
The months with the highest visibility are February, April, May, June, July, August, September, October, November and December (10km).
The months with the lowest visibility are January and March (9km).
